In case you didn't know yet, Flash Builder 4 beta (the product previously known as Flex Builder) is now available for download on labs.adobe.com, as is the beta for Flash Catalyst.
I've been playing around with the public beta for a little bit and thought it was worth blogging some of my favorite features in this release when it comes to features in the IDE. Up until now I've only tested it with pure ActionScript projects, so might discover some more gems later on.

Generating getter/setter methods

This is a huge time saver, you can now just define your class properties, right-click and select Source > Generate Getter/Setter and you get a useful dialog allowing you to specify how you want that getter and setter method set up. You can make your class property private, rename it, specify if you want the getter and/or setter, set up its access modifier and even define where you want those generated methods to get added in your code.

SWC introspection

If you work with library projects or third party SWC files you can now introspect those and figure out its packages, classes and methods. SWC files generated with Flash Builder 4 can also have their ASDoc comments embedded.

ASDoc integration

ASDoc is a tool that comes with Flash Builder for generating documentation from Javadoc style comments in your Flash Builder projects. There's now a panel that shows the documentation for a selected property or instance, you also get a tooltip showing the documentation when you hover over them.

As mentioned earlier this also works with SWC files generated from Flash Builder 4, since those can now contain the ASDoc information (increases SWC filesize, but not filesize when exporting a release build).

Be sure to give Flash Builder beta a try yourself, I'm very pleased with what I've seen so far and am sure it will improve productivity significantly.